Adakites have a distinct chemistry that links them to melting of a
mafic source at high pressure. They have been attributed to melting of
subducted oceanic crust or melting of the mafic crustal roots of thick
continental arcs, and are an important contrast to mantle wedge melting
as a means of generating continental crust. We report the first direct
evidence for the generation of adakitic melts in mafic lower
continental crust, in an exhumed Cretaceous arc in the South Island of
New Zealand. The lower crustal Pembroke Granulite has the bulk
chemistry and partial melting textures involving peritectic garnet
appropriate for a source region for an adakitic melt. The melt migrated
from the area through a fracture network now filled with trondhjemitic
veins. Emplacement of the melt was in the upper crust of the Cretaceous
section, illustrated by the presence of coeval adakites in the upper
crustal Nelson-Westland region.